net: Fix data-races around weight_p and dev_weight_[rt]x_bias.

stable inclusion
from stable-v4.19.257
commit d6be3137d5b9b5e9c6828d4d7eb7d73141895c7f
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I5UQH4


CVE: NA

--------------------------------

[ Upstream commit bf955b5ab8f6f7b0632cdef8e36b14e4f6e77829 ]

While reading weight_p, it can be changed concurrently.  Thus, we need
to add READ_ONCE() to its reader.

Also, dev_[rt]x_weight can be read/written at the same time.  So, we
need to use READ_ONCE() and WRITE_ONCE() for its access.  Moreover, to
use the same weight_p while changing dev_[rt]x_weight, we add a mutex
in proc_do_dev_weight().

Fixes: 3d48b53f ("net: dev_weight: TX/RX orthogonality")
Fixes: 1da177e4 ("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Yongqiang Liu <liuyongqiang13@huawei.com>